Several types of pointing devices are in use in information display systems. The devices of the prior art are represented by Laman, U.S. Pat. No. 3,269,190; Gersten, U.S. Pat. No. 3,395,589; Brown et al, U.S. Pat. No. 3,643,148; Rider, U.S. Pat. No. 3,835,464; Opocensky, U.S. Pat. No. 3,987,685; Thornburg, U.S. Pat. No. 4,313,113; and Alexander, U.S. Pat. No. 3,013,441.
Other positioning devices in current use in computer control systems are popularly known as: a mouse, a touch screen, cursor keys, a digitized pad with an electronic pen, a light pen, a joystick and a trackball.
A specific limitation of many of the devices of the prior art and the popularly marketed devices is that the degree of precision control available is crude compared to the power and precision of the data processing devices themselves and detection of fine movements of the imput devices are a particular limitation. Another reason for the lack of precision is that the devices are difficult to control because they do not conform to the user's ordinary motor skills and capabilities of the human musculature.
This invention seeks to provide greater precision and to conform more closely to the operator's motor skills developed over his lifetime. Largely control of drawing and pointing operations is developed through eye-hand coordination and feedback in the common tasks of drawing and writing with pen and paper. These same arm, hand and finger movements are captured as input by the present invention and reflected on a computer screen to provide visual feedback, simulating the eye-hand coordination of writing operations. The present device provides two-level control. First, gross movement input from arm muscle action is transmitted through the thumb and middle finger grasping the outer cover of the pointing device which moves throughout a detectable range relative to the fixed base. Second, fine detail is controlled by the index finger resting on a small cup that glides easily along a spherical surface approximating the natural path of the finger tip as it pivots on its joints.
Other control movements may also be incorporated in the design of the control device. For example, a switching action can be provided by downward pressure on the finger cup by the index finger. This is analogous to pressing a writing implement against paper to leave a mark or continuous line or to vary the width of a line.
The device integrates these three input movements allowing the operator to utilize, in his discretion, the same skills developed with pencils and pens but with the hand remaining in substantially the same place on the device. Since the device is symmetrical, it can be operated from either hand.
An objective being a multi-purpose control device, it can be seen that the cited references and devices now marketed are functionally limited in that they either require considerable flat surface area for movement such as with a mouse. Some require taking one hand off of the regular control devices such as the keyboard. All have a low resolution capability. There is thus a need for a pointing device which is at once capable of broad and fine detail that does not require large surface area for operation, can be conveniently keyboard mounted and combines accuracy, convenience and low cost.